Excerpted from LEED 2009 for Healthcare
To provide building occupants with a connection between indoor spaces and the outdoors through the introduction of daylight and views into the regularly occupied areas of the building.
Install daylight responsive controls in 100% of the area that meets the daylight quantity thresholds above. Daylight controls must switch or dim electric lights in response to the presence or absence of daylight illumination in the space.
For a minimum of 75% or more of the perimeter area used to qualify under IEQ Credit 8.2, achieve daylighting in at least the following spaces1, through 1 of the 4 options:
Demonstrate through computer simulations that 75% or more of perimeter area used to qualify under IEQ Credit 8.2 achieve daylight illuminance levels of a minimum of 10 footcandles (fc1. A footcandle (fc) is a measure of light falling on a given surface. One footcandle is defined as the quantity of light falling on a 1-square-foot area from a 1 candela light source at a distance of 1 foot (which equals 1 lumen per square foot). Footcandles can be measured both horizontally and vertically by a footcandle meter or light meter.
2. The non-metric measurement of lumens per square foot, one footcandle is the amount of light that is received one foot from a light source called a candela, which is based on the light output of a standardized candle. A common range for interior lighting is 10 to 100 footcandles, while exterior daytime levels can range from 100 to over 10,000 footcandles. Footcandles decrease with distance from the light source. The metric equivalent of a foot candle is 10.76 lux, or lumens per square meter.) and a maximum of 500 fc in a clear sky condition on September 21 at 9 a.m. and 3 p.m.
Provide glare control devices to avoid high-contrast situations that could impede visual tasks. However, designs that incorporate view-preserving automated shades for glare control may demonstrate compliance for only the minimum 10 fc illuminance level.
For sidelighting zones:
For toplighting zones:
Demonstrate through records of indoor light measurements that a minimum daylight illumination level of 10 fc and a maximum 500 fc has been achieved in at least 75% of the perimeter area used to qualify under IEQ Credit 8.2. Measurements must be taken on a 10-foot grid for all occupied spacesEnclosed space intended for human activities, excluding those spaces that are intended primarily for other purposes, such as storage rooms and equipment rooms, and that are only occupied occasionally and for short periods of time. Occupied spaces are further classified as regularly occupied or nonregularly occupied spaces based on the duration of the occupancy, individual or multioccupant based on the quantity of occupants, and densely or nondensely occupied spaces based on the concentration of occupants in the space. and recorded on building floor plans.
Provide glare control devices to avoid high-contrast situations that could impede visual tasks. However, designs that incorporate view-preserving automated shades for glare control may demonstrate compliance for only the minimum 10 fc value.
Any of the above calculation methods may be combined to document the minimum daylight illumination in at
least 75% of the perimeter area used to qualify under IEQ Credit 8.2.
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Sr. Project Architect
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